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West Pacific/2015/09W/Archive/9
Public advisory TROPICAL STORM CHAN-HOM PUBLIC ADVISORY NUMBER 9 WIKI-HURRICANES FORECASTING CENTER 12:00 PM JST THU JUL 02 2015 ...CHAN-HOM STEADY IN INTENSITY WELL SOUTHEAST OF GUAM... SUMMARY OF 12:00 PM JST...03:00 UTC...INFORMATION ------------------------------------------------------------------- LOCATION...11.3N 151.1E CENTER POSITION CONFIDENCE: GOOD ABOUT 570 MI...915 KM WNW OF PALIKIR, MICRONESIA ABOUT 450 MI...725 KM ESE OF GUAM MAXIMUM SUSTAINED WINDS...50 KT...60 MPH...95 KM/H MINIMUM BAROMETRIC PRESSURE...996 MB...29.41 INCHES PRESENT MOVEMENT...WNW AT 16 KT...18 MPH...29 KM/H DISCUSSION AND 48-HOUR OUTLOOK --------------------------------------------- At 6:00 am JST, the center of Tropical Storm Chan-Hom was situated near 11.3N, 151.1E, about 570 miles (915 km) west-northwest of Palikir, Micronesia, or about 450 miles (725 km) east-southeast of Guam. Maximum sustained winds were 50 knots (60 mph, 95 km/h), with higher gusts. The minimum barometric pressure was 996 millibars (hPa; 29.41 inHg), and the cyclone was tracking west at 16 knots (18 mph, 29 km/h). Steady strengthening is expected over the next 48 hours, succeeded by more rapid intensification thereafter. On its current forecast track, Chan-hom poses a substantial threat to the central and southern Mariana Islands, and residents there should monitor the progress of the cyclone closely. NEXT ADVISORY ------------------- Next complete advisory at 6:00 pm JST. $$ Forecaster TAWX14 Discussion TROPICAL STORM CHAN-HOM DISCUSSION NUMBER 9 WIKI-HURRICANES FORECASTING CENTER 12:00 PM JST THU JUL 02 2015 Tropical Storm Chan-hom continues to be disorganized this evening. After remaining obscured for a majority of the day, the low-level circulation is partially exposed on the edge of the system's cirrus canopy. In addition, associated shower and thunderstorm activity appears more oblong compared to this morning. Despite this apparent decrease in organization, recent satellite estimates were T3.0/45kt from SAB, T3.5/55kt from JTWC, and T3.1/47kt from UW-CIMSS ADT. As a result, the initial intensity has been held at a potentially generous 50kt. Based on the cyclone's satellite presentation, Chan-hom continues to feel the effects of moderate easterly wind shear via a displaced upper-level area of high pressure. In fact, maps from UW-CIMSS indicate that these strong upper-level winds are persistently on the magnitude of 20 to 30 knots. Another potential inhibitor is the quick forward motion of the cyclone, which may be introducing speed shear in an already unfavorable environment. However, over the coming days, the upper-level setup is expected to become exceptionally conducive as an anticyclone builds aloft. An upper-level low moving north to the cyclone's north should also provide a poleward outflow channel, beneficial to the storm's intensification rate. Sea surface temperatures and ocean heat content values are also expected to remain conducive for further organization. Both global and hurricane models continue to indicate that Chan-hom will become a large and powerful typhoon over the coming days, with all guidance suggesting a pressure under 930mb by day 5. As such, the updated intensity forecast follows the previous in showing steady intensification over the next 48 hours or so, but it once again shows a quicker rate of strengthening thereafter. It would not be at all surprising if a Category 5-equivalent cyclone was traversing the West Pacific by the end of the forecast period. As has been the case most of the day, Chan-hom is continuing on a swift westward motion. The forecast philosophy for the storm is unchanged. The cyclone is being steered on its current direction via an expansive mid-level ridge to its north. Global modelling suggests that this ridge may even intensify over the coming day or so, forcing Chan-hom on a west-southwest track. However, by 48 hours, a series of upper-level troughs digging into Japan and surrounding regions is expected to erode the western periphery of the ridge and force the tropical storm on a northwesterly course. The updated forecast track is very close to the previous one. On the current path, Chan-hom is expected to pose a substantial threat to the central and southern Mariana Islands. INIT 02/0300Z 11.3N 151.1E 50 KT 60 MPH 12H 02/1200Z 11.3N 149.6E 50 KT 60 MPH 24H 03/0000Z 11.1N 148.2E 60 KT 70 MPH 36H 03/1200Z 11.3N 147.3E 70 KT 80 MPH 48H 04/0000Z 12.2N 146.4E 85 KT 100 MPH 72H 05/0000Z 15.3N 144.0E 100 KT 115 MPH 96H 06/0000Z 18.5N 141.9E 120 KT 140 MPH 120H 07/0000Z 21.3N 138.8E 140 KT 160 MPH $$ Forecaster TAWX14